<p>Network protocol designers face difficult tasks, including simultaneously monitoring state in a potentially large number of nodes, understanding and analyzing complex message exchanges, and characterizing dynamic interactions with competing traffic.</p> <p>Researchers have explored network protocol visualization in many contexts, beginning with static protocol graphs and visualization of large-scale traffic, and more recently including simulation visualizations and editors. Network visualization tools allow designers to take in large amounts of information quickly, visually identify patterns in communication, and better understand causality and interaction.</p> <p>Nam is a network animator that provides packet-level animation, protocol graphs, traditional time-event plots of protocol actions, and scenario editing capabilities. Nam benefits from a close relationship with ns, which can collect detailed protocol information from a simulation. The authors describe how nam uses preprocessing to visualize data taken directly from real network traces. They also feel that visualization tools such as nam make protocol design and debugging easier.</p>